In Patent Literature 1, a technology concerning a method for producing carbon nanotubes (CNTs) is described. In the method described in this literature, first, clusters are made. That is, clusters are made by filling mixed gas of helium and methane in a vacuum vessel and applying current between two graphite rods, into which catalyst metal such as nickel is embedded, in the vacuum vessel to cause discharge. Next, after the clusters thus made are collected, the clusters are deposited on a silicon substrate by vacuum deposition. Then, synthesis of carbon nanotubes are performed using the micro wave plasma CVD method.
In Patent Literature 2, a method for easily producing vertically oriented carbon nanotubes and producing elongated carbon nanotube fibers and the like from the vertically oriented carbon nanotubes is disclosed.
In Patent Literature 3, a technique for elongating carbon nanotubes by adding an oxidizing agent such as water in a reaction atmosphere at the time of growing carbon nanotubes is disclosed.